Meisak Darya, Macutkevic Jan, Plyushch Artyom, Kuzhir Polina, Selskis Algirdas, Banys Juras
Vilnius University, Sauletekio Ave. 3, LT-001222 Vilnius, Lithuania.
Institute for Nuclear Problems, Belarusian State University, Minsk 220006, Belarus.
Polymers (Basel). 2020 Mar 21;12(3):697. doi: 10.3390/polym12030697.
The electrical properties of epoxy/MWCNT (multi-walled carbon nanotubes)/MnFeO hybrid composites loaded with MWCNTs (below, 0.09 vol.%, and above, 0.58 vol.%, percolation threshold) and varying concentrations of MnFeO up to 10 vol.% were studied in a wide frequency range (20 Hz-40 GHz) at different temperatures (20 K-500 K). At low frequencies, the dielectric permittivity and the electrical conductivity of composites with fixed amounts of MWCNT are strongly dependent on MnFeO content. For MWCNT concentrations above the percolation threshold (i.e., 0.58 vol.%), the electrical conductivity highly decreases with the increase of the MnFeO fraction. In contrast, for the epoxy/MWCNT just below the onset of electrical conductivity (0.09 vol.% of MWCNTs), there exists an optimal concentration of MnFeO inclusions (i.e., 0.025 vol.%), leading to a dramatic increase of the electrical conductivity by three orders of magnitude. The electrical transport in composites is mainly governed by electron tunneling at lower temperatures (below 200 K), and it is highly impacted by the matrix conductivity at higher temperatures (above 400 K). The electrical properties were discussed in terms of the Maxwell-Wagner relaxation and distributions of relaxation times. A non-invasive platform based on dielectric relaxation spectroscopy was proposed for enhancing the synergetic effect coursed by using multiple nanoinclusions in polymer composites just below the percolation threshold.
研究了负载有MWCNT（低于渗流阈值时为0.09体积%，高于渗流阈值时为0.58体积%）且MnFeO浓度变化高达10体积%的环氧/MWCNT（多壁碳纳米管）/MnFeO混合复合材料在宽频率范围（20 Hz - 40 GHz）和不同温度（2% - 500 K）下的电学性能。在低频下，固定MWCNT含量的复合材料的介电常数和电导率强烈依赖于MnFeO含量。对于高于渗流阈值（即0.58体积%）的MWCNT浓度，电导率随着MnFeO含量的增加而显著降低。相反，对于刚好低于导电起始点的环氧/MWCNT（0.09体积%的MWCNT），存在一个最佳的MnFeO夹杂物浓度（即0.025体积%），导致电导率急剧增加三个数量级。复合材料中的电输运在较低温度（低于200 K）时主要由电子隧穿控制，而在较高温度（高于400 K）时受到基体电导率的强烈影响。根据麦克斯韦 - 瓦格纳弛豫和弛豫时间分布对电学性能进行了讨论。提出了一种基于介电弛豫光谱的非侵入性平台，用于增强在略低于渗流阈值的聚合物复合材料中使用多种纳米夹杂物所产生的协同效应。
